1. Field of the Invention
The present invention relates to an apparatus for separating oil from water. and more particularly, to an oil skimmer assembly which has an endless belt for removing oil from the surface of water.
2. Description of Related Art
With oil skimmers utilizing endless belts, typically, the belt :is suspended from a driven head pulley. The belt is also passed around a tail pulley that is positioned in a body of water. When the head pulley is rotatably driven, a descending reach of the belt on entering the body of water will pick up surface oil and carry that oil around the tail pulley to an ascending reach of the belt. Wipers are positioned below of the head pulley near the top of the descending reach to scrape oil from the surface of the belt. Collection pans positioned below the wipers receive the separated oil and deliver the separated oil to a collection vessel for recycling or appropriate disposal.
In the past, the tail pulleys have usually either been mounted in a vessel containing the oil and water to be separated or alternately, supported exclusively by the belt. As an example of the latter, if oil is to be removed from a contaminated water well, an elongated belt supporting a tail pulley is dropped into the well, and the weight of the pulley and the belt provide belt tension. Clearly, if the belt breaks, there is a problem because the pulley will be dropped into the well and either lost or, at best, retrievable only through a successful "fishing" operation. Even if the belt does not break, on occasion, a pulley will slip out of the belt as the belt is lowered or during operation, and once again, an operator has, at best, a difficult retrieval process to confront.
Even where tail pulleys are not rotatably mounted in tanks but are supported by the belt, other problems manifest themselves. If the axis of rotation of the head pulley is not properly oriented, the belt will not track properly and excessive wear can occur. If the belt is steel, the wear is exacerbated and considerable damage can be caused to both the belt and the head pulley. Further, if the head pulley is equipped with magnets to drive the belt, a misaligned magnet or protruding magnet can cause excessive belt tension that results in belt failure.
Another problem is that when endless belt oil skimmers are used in quiescent bodies of water, their efficiencies can be relatively poor. The relatively poor efficiency is due to the fact that the belt picks up oil as it enters a water body and if the body is quiescent, the surface in the vicinity of belt entry soon becomes relatively oil free. Further, pick-up must wait for a relatively slow from portions of the body surface remote from the belt entry migration of oil location.